关键词: 合成孔径雷达（SAR）, 数字高程模型（DEM）, 直接正射校正, 间接正射校正

Abstract: For the direct and indirect ortho-rectification of SAR image based on DEM, this paper gives the difference analysis for the theory, steps, correction effect and applicability. Moreover, it makes a comparison for the correction accuracy are based on the orthographic corrected high resolution satellite image. Experimental results illustrate that although the two methods are based on the same model, the start points are different, the steps and computational complexities as well as the correction effects are also different. But the correction accuracy difference between the two methods is very small. Both can meet the demand of the correction accuracy and the appropriate method should be chosen according to actual situation.

Key words: Synthetic Aperture Radar（SAR）, Digital Elevation Model（DEM）, direct ortho-rectification, indirect ortho-rectification